I gave birth to my baby 2 weeks ago, and have noted that his left arm is flabbier than his right. I often try to get him to move it, but it’s not easy on his own. I don’t know if I should see someone soon, or wait for my follow-up appointment in 2 weeks. Thanks for your help, Sophia

Thank you for asking about this, and I think you did a good thing noting that one arm has less tone only after 2 weeks.

I don’t know how your delivery went, Sophia, but this can occur if it was more complicated, with longer pushing, a bigger baby, a shoulder that was more difficult to exit, diabetes, or if forceps were used. We call this phenomenon perinatal brachial plexus palsy. It’s a big term that indicates that one arm is more hypotonic than the other, with less strength, slower reflexes and less movement than the other.

You need to talk about this with your doctor, who will do a full physical exam of your baby to check for this issue. Don’t be surprised if he asks for a shoulder and arm x-ray to determine the potential cause. 75% of perinatal brachial plexus palsy situations disappear on their own after about one month. You should also see an osteopath or pediatric physiotherapist to learn how you can position the baby and learn about exercises you can do with him.

If total recovery doesn’t seem to be occurring or is taking more time, you may be referred to a multidisciplinary team that can develop an intervention strategy for your baby. But for now, keep observing your baby to see if the situation improves or becomes worse. If the latter occurs, try to see your doctor sooner if possible.

All my best,


The Baby Expert

Il est bien aussi de rencontrer une ostéopathe ou une physiothérapeute pédiatrique pour avoir des idées de positionnement du bébé et des exercices spécifiques à faire avec lui.

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